The overall objective of this project is to investigate the pathologic changes of papilledema using light and electron microscopy, to study the pathophysiologic processes of axoplasmic autography, to examine the disturbance of vascular dynamics in papilledema using horseradish peroxidase tracer technique and to investigate the pathogenetic mechanisms, which produce papilledema. Experimental papilledema will be produced in rhesus monkey by ocular hypotony, increased in intracranial pressure, increased in intraocular pressure, and experimental allergic encephyllitis. We show collect additional human materials of papilledema secondary to increased intracranial pressure, and decreased in intraocular pressure for pathologic study.